Hundreds of residents on the nearby island of Yeonpyeong, off the west coast of the Korean peninsula, were evacuated to shelters after warning sirens were sounded, but the incident quickly passed.

The South Korean navy patrol boat was on the southern side of the Northern Limit Line at about 6 p.m. local time (5 a.m. ET) when a North Korean navy ship fired two artillery shells, defense officials told NBC News.

The shells did not hit the South Korean ship and fell in waters near it. The South Korean ship then fired several artillery rounds in waters near the North Korean ship, the Yonhap news agency reported.

“The South Korean defense ministry has sent an official protest letter via the military communication line between South Korea and North Korea,” the official said. “The South Korean military severely warned the North that the North is responsible for this provocation and the South Korea military will carefully watch the situation."

Both Koreas regularly conduct artillery drills in the disputed waters and the Northern Limit Line - a maritime boundary unilaterally drawn by the U.S.-led U.N. Command at the end of the 1950-53 Korean War - has been the scene of three bloody naval skirmishes since 1999.

North Korea has in recent weeks conducted a string of artillery drills and missile tests and has unleashed a torrent of rhetoric at the leaders of the U.S. and South Korea.